Job Number

0101-18

Equipment type

28 inch Monitor

Maker + Model #

Hantarex MTC 90028SR

Made in

West Germany

Client Info

Patrick Micallef (David Sammut friend) – tel 826963

Comments

Since the doc was written long after the fault, a summary of the fault is produced.

BAD

1

Tv turns off to stand by mode immediately after switch on.

GOOD

1

Full repair description and observations

1

Initially, the voltage supply was under suspicion. 3 voltage regulators were found attached to a heat sink. They were disconnected and tested, but were found to be perfect. It was noted that 2 of them had the collector (back metal from were regulator is screwed to heat sink) in direct contact with the heat sink (earth). A plasic sheet was used as an insulator between the regulator back metal and heat sink. However this did not solved the problem.

2

After analysing the circuit and various line voltages, it was concluded the line output transformer (LOPTX) was shorted/faulty. It was disconnected and two cracks were visible in the epoxy casing.

3

The original LOPTX was not found for sale, but a HR-LOPTX equivalent was bought instead. The conversion from the old LOPTX to the equivalent HR-Diemen model can be easily checked from the HR site at: www.hrdiemen.es.

4

The replaced LOPTX solved the problem, and a picture with sound was obtained.

5

However, a small fault which the client complained about was still present. In some cases, the picture will roll vertically, especially at weak stations or very bright pictures from the video.

6

The vertical hold pot helped a little to stabilize the picture but was still not perfect. A new pot was replaced and things improved a lot - the picture would shake on very very few occasions. Nothing could be done to improve this fault to perfection.

7

Some dry joint at the video input were fixed up. The client saw the TV working and did not phone back to quarrel about any fault.

Repair summary

LINE OUTPUT TRANSFORMER FAULTY